The synthesis and characterization of a series of cationic copper(II) complexes of the type [Cu(NCR)6][Al(OC(CF3)2R′)4]2 (R = CH3, Ph; R′ = CF3, Ph, PhCH3), incorporating poly/perfluoronated alkoxyaluminates as weakly coordinating anions (WCAs) is presented. Aziridination of various olefins, such as the unreactive olefinse.g.ethylhex-2-enoate and 1-decene, with N-tosyliminophenyliodinane catalyzed by [Cu(NCR)6][Al(OC(CF3)2R′)4]2 affords very good yields (up to 96%) and high TOFs (up to 5000 h−1) under mild conditions. Using disubstituted olefins as substrates, high stereoselectivities are obtained at room temperature. The to date highest cis : trans ratio (98 : 2) of the obtained aziridines is achieved for cis-stilbene in good yield (85%) as well as promising TOF (> 2000 h−1). The investigation of the solvent effect on yield and selectivity reveals that for certain oleophilic substrates (1-decene), less polar solvents, such as dichloromethane are a better choice than acetonitrile, which is commonly considered as the best solvent for olefin aziridination. Accordingly, a mechanism involving a paramagnetic copper nitrene intermediate with both concerted and stepwise pathways is proposed.
You have access to this article
Please wait while we load your content...
Something went wrong. Try again?